The process of manufacturing luminaires for fluorescent lighting has been improved and refined to such a high degree that there are almost no opportunities left for further cost reductions.
The present invention features a means for combining an electronic ballast with one or more fluorescent lamp connectors to form a single, easy-to-assemble, relatively light weight integrated fixture. By transferring a relatively small amount of materials cost from a luminaire to the fixture, the luminaire manufacturer minimizes the additional wiring needed to wire a luminaire, eliminates the need for certain parts in the luminaire, and eliminates several manufacturing processes. Thus, the integrated electronic ballast fixture offers a significant overall cost reduction to the luminaire manufacturer. The reduced installation time also benefits those who replace or upgrade ballasts at locations remote from the luminaire manufacturer.
The integrated electronic ballast fixture is designed for high-speed, low-cost manufacturability. This is accomplished by minimizing the amount of manual labor needed. To reduce the design cycle time and minimize capital expense, the fixture was designed to be able to use off-the-shelf lamp connectors. Electrical connections to the fixture (AC power input, connections to the other end of lamps, lamps, dimmers, etc.) may be implemented as wires and/or one or more connectors, such as of the poke-in or wire-trap varieties. Even though the fixture is typically longer than a standard ballast, it is relatively light-weight since no potting compound is used.
A basic tenet of luminaire manufacturers has been to not allow changes (and in particular increases) to certain luminaire dimensions, such as the overall length, width, and thickness, in order to maintain backward (compatibility with existing luminaires. Because of this design constraint, it is extremely difficult to offer a single integrated ballast fixture that can accommodate all combinations of up to four linear or U-shaped lamps to meet all applications. However, a given integrated fixture design with specific lamp spacings can easily accommodate different quantities and types of lamps. Thus, the integrated fixture of this invention provides a certain degree of universality.
The integrated electronic ballast fixture of this invention is believed to be a major breakthrough for the lighting industry, not only as a cost reduction, but also for its increased reliability. The ballast operates at a lower temperature compared to a standard form-factor enclosure, because the power being lost (in the form of heat) in ballast components such as transformers, resistors, and semiconductors is dissipated over a greater area in a larger volume. Also, since more space is available, components operating at higher temperatures can be spaced further apart to reduce additional heatup. If one or more components, such as a transformer, runs at a temperature higher than desired, further thermal enhancement may be included to increase the operating life. Since heat is dealt with by other means, the fact that this fixture uses no potting compound greatly enhances reliability. Differences of the thermal coefficient of expansion between conventional potting compounds and various electronic components in prior ballasts may cause premature cracking of solder joints, thereby rendering those ballasts inoperative.
The electronic ballast circuitry of the present invention may include components for additional features such as step-dimming, automatic lamp current correction, lumen maintenance, automatic ambient light sensing, and remote ballast control. Sensors for functions such as automatic ambient light sensing may be attached directly to the fixture or may be mounted remotely. Also, the inclusion of more than one ballast, as well as the use of other ballast technologies (e.g., magnetic ballasts), instead of electronic ballasts in the fixture, is well within the scope of this invention.